Summary of Proposed Work. Experiments are being conducted to study the effects of steroid hormones progesterone and estradiol on the synthesis and secretion of proteins by cultured epithelial cells derived from the porcine uterus and fallopian tubes, and by explants by porcine endometrium. Particular attention will be paid to those proteins which are normally found specifically in uterine secretions during the luteal phase of the estrous cycle and during pregnancy. One of these proteins, the purple phosphatase is induced by progesterone in the intact animal and is relatively easy to purify and identify. We have shown that this enzyme is secreted by cultured explants from pregnant endometrium but not by explants from non-pregnant tissue taken from animals early in their estrous cycles. The work proposed for the next 12 months has the following major objectives 1. To improve our ability to maintain and grow uterine epithelial cells over extended periods of time. Research will largely center on a) attempts to use enzymes to free larger numbers of epithelial cells from the endometrium and to establish cultures from these, b) improvements in culture conditions, possibly incorporating an underlying layer ("feeder layer") of dead or inactivated fibroblasts. 2. To use combination of progesterone, estradiol and possibly polypeptide hormones such as placental lactogen to induce the synthesis of the purple phosphatase in cultured uterine epithelial cells and endometrial explants taken from animals early in their estrous cycles when they do not produce the purple phosphatase in vivo.